Posted Tue Jun 12, 2012, 12:36pm Subject: Re: autofill problems
Missed the previous two posts and saw the last one.
If you disconnect the auto-fill wire and the boiler fill is not starting then it is not the probe. Since it is intermittent then I also suspect electronics. That is what had me saying the black box should be opened up and checked as well as all the connection points for tight fit and corrosion.
There is probably a relay inside the black box that sends the electricity to those two components. I would say that is the prime area of fault, but it is electronics, so a LOT of things are possible.
Odds are that a replacement box would solve the problem. You know the auto fill works sometimes and you know that the pump works correctly. Doesn't leave much other than what I said here and mentioned in my first post...
jpboyt Senior Member Joined: 28 May 2010 Posts: 22 Location: Washington, USA Expertise: I love coffee
Posted Wed Jun 13, 2012, 1:49am Subject: Re: autofill problems
I would suspect the DC power supply is no longer providing clean DC to energize the relays. This type of problem seldom looks the same two times in a row as temperature and load changes the DC voltage level and the content of unrectified AC. In other words, you have a dead or dying capacitor in the DC power supply. Either replace the board or send it to someone like myself that specializes in espresso electronics for repair. jpboyt
jpboyt Senior Member Joined: 28 May 2010 Posts: 22 Location: Washington, USA Expertise: I love coffee
Posted Wed Jun 13, 2012, 8:28am Subject: Re: autofill problems
I'm having a hard time seeing details from your photo but it looks like you have a small daughter card for each high voltage item on the motherboard. I would suspect that the "blue box" on each card is a relay, power transistor, or triac. I can't see it well enough to determine. If you can photo the side with the part mark (of the blue device) we can determine what it is. The small white chips are optocouplers. Low voltage on one side of the chip and low or high voltage on the other. Somewhere on every board there is a division of high voltage (Mr. Snappy) and low voltage for control devices. This division can happen at a relay or at an opto-coupler. This chip will turn on a relay or a triac and can control either a low or high voltage device. Interesting set up. I have not seen this technique of replaceable daughter cards used in espresso equipment before. Electronics are a lot like engines. Once you understand what has to happen you then can start identifying parts as to function. jpboyt
ryecarr01 Senior Member Joined: 2 Nov 2011 Posts: 44 Location: north east Expertise: Just starting
Posted Thu Jun 14, 2012, 1:19am Subject: Re: autofill problems
the PCB is currently with a guy who is replacing some of the componenets on it, i should have it back later today but obviously unable to take any photos at the moment.
before i sent i off i was swapping the detachable boards about (each one seems to control a solenoid valve, there are 4, 3 groups and the autofill) and each detachable board would work anywhere in on the PBC, apart from the autofill.so it would appear they are all ok?
i will post with the outcome later on when i get t back, although he did say not to get my hopes up as he doesnt think replacing any of the parts will make a difference, but for £35 it is worth a shot right??
ryecarr01 Senior Member Joined: 2 Nov 2011 Posts: 44 Location: north east Expertise: Just starting
Posted Mon Jun 18, 2012, 4:49am Subject: Re: autofill problems
ok this is getting really annoying and repetitive now, can someone reccomend a UK based (preferbly North) electronics guy or decent espresso engineer to look at this board. I have had 2 "experts" with electronics telling me that the board is fine and they cant see anything wrong with it. its like banging my head against a brick wall.
maybe it isnt the board but there is nothing else it can be??is there???
should i have any sort of voltage at all when testing between my probe and the earthing of the machine?? i have 12v and not sure if this is normal or not???
i know my only other option is to buy a new board but have you seen the proce of those things?? and the place where I would buy it from stipulates that PCB's cannot be returned so I would then be royally screwed.
most people on here seem to only have experience with small domestic machnes so if someone could point me in the direction of someone with knowledge of commercial machiens that would be great
Posted Mon Jun 18, 2012, 7:57am Subject: Re: autofill problems
As I have mentioned, remove the wire from the water-level probe. When removed from the probe, the machine should begin filling the boiler. Ground the wire and the water refill should stop. That's it. If that does not operate as described, remove that individual wire from its connection at the black box. When that one wire is removed from the black box, it should operate the same way. Connecting a test lead to the connection point on the box and touching the other end to ground should stop autofill. Removing that end from ground should start autofill. It should either make the fill solenoid click OR it should make the motor start, or both.
If there is no safety switch like one that turns the machine off when the water level in a reservoir is low on water,, and you are sure power is getting to the black box and other devices properly, and all the other systems have been checked as mentioned above, then the box is probably bad. You have established that the motor runs sometimes, and the solenoid clicks sometimes and you can pull shots sometimes. That all points to a bad control system. Components that work properly on a workbench may not work properly when hot or under load.
How much is a new box? How much time have you spent? How much has not finding out cost you? How much peace of mind have you lost? What would be the worst case? You buy the box and it doesn't fix the problem? There is little left to change, and now you have a spare box.
ryecarr01 Senior Member Joined: 2 Nov 2011 Posts: 44 Location: north east Expertise: Just starting
Posted Tue Jun 19, 2012, 8:34am Subject: Re: autofill problems
turns out the pcb i require is pretty much obselete :(
so, my PCB works on all fronts apart from the autofill, cant i just add another autofill box that only controls the autofill and the orginal PCB left to control the groups?
i have found a water level relay from a one group machine, this should work right?
im assuming i would need a feed in, my probe feed in, and feeds out to the appropriate solenoid and motor?
jpboyt Senior Member Joined: 28 May 2010 Posts: 22 Location: Washington, USA Expertise: I love coffee
Posted Tue Jun 19, 2012, 2:25pm Subject: Re: autofill problems
Adding an autofill box is not an option as the control you have shuts off the boiler solenoid when you pull a shot. If the machine happens to be filling when you pull a shot the control removes power to the autofill solenoid to prevent water going to the boiler rather than the grouphead. Have your electronics folks check the capacitors near the autofill probe wire connector. The autofill probe wire normally sends out some sort of square wave signal, not a constant DC voltage. As the tank fills this signal is grounded and the signal is pulled low at a logic chip. I have found that capacitors that have dried out have caused problems. Your problem is not with relays, you swapped them to test, or with logic from the microcontroller, you are not seeing voltages when there should be no voltage. Your problem is with the logic that is being provided to the micro-controller. Garbage in/ Garbage out. You are discovering why certain controllers died and were replaced by redesigned controllers. The autofill circuits seem to be the most susceptible to scale and decaying component performance of all the circuits. I'm still willing to look at your box. jpboyt
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